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(No Model.) 3 Sheets-Sheet 1. W. OESTERREIOH. TELEPHONE SWITGHBOARD.

No. 479,107. Patented July 19, 1892.

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Patented July 19, 1892.

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(No Model.) Q a sheets-sheet 3. W. OESTERBEIOH.

TELEPHONE SWITGHBOARD. v v No. 479,107. Patented July 19, 1892.

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NII'TED' STATES ATENT OFFICE.

WILHELM OESTERREIOI-I, on BERLIN, GERMANY, ASSIGNOR TO MIX & GENEST, on SAME PLACE.

TELEPHONE-SWITCHBOARD.

SPECIFICATION forming part of Letters Patent No. 479,107, dated July 19, 1892.

Application filed August 7, 1889- Serial No. 320,009-- (No model.) Patented in Germany March 16, 1887, No. 45,143; in Austria- Hungary June 28,1888,N0. 27,801 and No. 9,268, and in Italy August 25, 1888, XLVII, 229.

T all whom, it may concern.-

Be it known that I, WILHELM OESTERREIOH, electrician, a subject of the King of Prussia, residing at 3 Yorkstrasse, Berlin, Prussia, German Empire, have invented certain new and useful Improvements in Multiplex Switchboards, (for which I have obtained Letters Patent in Germany, dated March 16, 1887, No. 45,143; in Austria-Hungary, dated June 28, 1888, No. 27,801 and No. 49,268, and in Italy, dated August 25, 1888, XLVII, 229;) and 'I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

Figure 1 is a sectional and diagrammatic view illustrating the connection of a telephone-line with three multiplex switchboards. Fig. 2 is a longitudinal section, and Fig. 3, a top plan view, of my improved jack-switch. Fig. 4 shows one of my improved switch-connecting plugs by a longitudinal and cross section, respectively, the latter section being taken on the line a 00 of the former section. Fig. 5 shows similar views of a line tester or plug. Fig. 6 is a view similar to Fig. 1, showing the connections between three multiplex switchboards and two telephone lines, respectively. Fig. 7 illustrates the line-tester or apparatus and the means for connecting the switchmans telephone with the telephoneline. Figs. 8 and 9 show by a longitudinal section and top plan view another form of jack-switch. Fig. 10 is a view similar to Fig. 6, illustrating simplified connections. Fig. 11 shows a simplified connection for a subscrib ers telephone with the line. Fig. 12 is aside View of the test-plug shown in Fig. 11. Fig. 13 is a view' similar to Fig. 10, showing the connections between the switches of four multiplex switchboards and the lines of four telephones; and Fig. 14 is a vertical transverse section of a multiplex switchboard, illustrating the relative arrangement of the switches.

The invention relates to multiplex switchboards for telephone exchanges, and more particularly to the Scribner system of switchboards as used by the Western Electric Gompany, of Chicago, and has for its object to simplify the construction of thejack-knife or for short jack-switches and their connections and interconnections, whereby a special testcircuitnecessary to these systems as well as a third insulated contact are dispensed with.

The further object of this invention is to so arrange the switch in the boards as to facilitate the operation of connecting the telephonelines and the testing of such lines.

In switch systems of the class referred to there is, besides the line-circuit that extends over the entire system of switchboards and connects the contact-springs of all the jackswitches, a line-circuit that connects the bodies of the switches with one another. The first-named line connects each of the telephone-lines with a switch-spring at the first board, the contacts of which springs are connected with the springs of the corresponding switches of the next switchboard, and so on throughout the entire system of switchboards in use. At the last board of the system the several contacts for the springs are electrically connected with a signal apparatus, from which the line goes to ground. The second line that connects the bodies of the switches forms a series of branch lines of the main line, so that a switchman at any one of the boards is enabled to ascertain whether there is already a connection between any one of the switches of his board and the main or telephone-line.

The invention consists in the connections between the switches of the different boards andthe telephone-lines and with the annunciator-drops and the switchmans call and test apparatus; also in the construction of the jack-switches and their arrangement in the switchboards, and in the construction of the test and connecting plugs, substantially as hereinafter fully described, and set forth in the claims.

Fig. 1 shows one method of connecting a telephone-line with its several switches at the different boards of a system, three such boards beingtherein shown. Each telephone-lineL has at each of the switchboards a jack-switch,

(indicated by I, II, and III,) such switch being composed of two parts only, as more plainly shown in Figs. 2 and 3na|nely, of the switchbody a, and contact-spring b. The switchbody a has atits front or outer end a short interiorly-threaded sleeve (1, by means of which it is screwed upon the sleeve a that serves as a supporttherefor and as a means to secure the switch into the front wall of the switchboard B", the sleeve a also serving as a means for supporting the connecting and test plugs hereinafter to be described.

The contact-springb is constructed with the re-entering angular portion or inwardlyprojecting knife-edge 0 and is connected with the switch-body a by means of a screw 1)", and is isolated therefrom by means of a plate or block 0, of any suitable material, such as ebonite or other like material. In its normal position the free end of the spring 1) lies in contact with the sleeve a of the switch-body, as shown at (Z, both elements of the switch being thus electrically connected,

the special contact for the spring heretofore used being dispensed with.

The telephone-line L is connected with the sleeve a of the switch-body a of the first board I, the spring of this switch being connected by wire 1 with the sleeve a of a switch-body of board II, the spring b of the latter switch being connected with the sleeve of a switch-body of board III, and so on throughout the series when more than three boards are included in the system. The spring I) of the switch at thelast switchboard is connected with the annunciator-drop K and the latter with a constant test-battery B, common to a number or to all of the switches of the last switchboard, the battery B being grounded, as shown at E, through an adjustable resistance \V.

By means of the adjustable resistance the line-current when the lines are not in use may be so regulated that it will neither influence the annunciatondrops K nor the telephone-alarms, but will be sufficiently strong to influence a sensitive test apparatus-such as a galvanoscope, for instance. To this end the relative power of the batteries W and B is so adjusted that the former will have a power of about 0.015 amperes and the latter of about 0.002 to 0.003 amperes, so that the call-current that energizes the electro-magnet of the annunciatorand of the subscribers call-bell is from five to six times stronger than that which influences the galvanoscope.

As is well understoocheach telephone of the system has a switch connection at the diiferent multiple boards at the central station and an annunciator-drop at one of the boards, the switchman of which last-named board attends to that particular telephone-that is to say, is charged with the connecting of that particular telephone with any other of the systems. To this end plugs are used that are connected, as is usual, by means of a wire, separate plugs being used for testing the line,

the test-plugs being connected with the galvanoscope by means of conductors s .9, Figs. 5, 6, and 7. The connectingplugs S consist of a solid cylindrical metallic plug k provided at its forward end with a pointed head 75 and an annular groove m, immediately in rear of said head, and in rear of groove m with a second annular groove, in which is fitted a ring at of ebonite or other suitable insulating material, as shown in Fig. 4.

The test-plugs S are of substantially the same construction, except that the body 7t of the plug from the groove in which the insulatorring at is fitted is of the same diameter throughout and that said body is inclosed in an insulating-ring n, over which is fitted a metallic cylinder h, this plug being, therefore,

composed-0f three parts, the metallic-headed plug-body 70, having the annular groove m, the insulation not, and the metallic cylinder h, which latter, as shown in Fig. 5, is completely insulated from the plug-body 70. Now if a connecting-plug S is introduced into a switch-body a a through the sleeve a so that the knife-edge 0 of the springb will lie in the annular groove m in rear of the head of the plug-body 7c, the plug is not only securely held in position, but the contact between the switch-body a and its spring I) is interrupted, while the said plug and spring I) will be electrically connected. If,on the other hand,a testplug S is introduced in a like manner, the direct electrical connection between the switchbody and spring I) will be interrupted and an electrical connection between the plug-body 7c and spring I), as well as between the switchbody a and the metallic ring it of the plug S, established. The telephone-line thus i11- terrupted between the switch-body and spring I) is now closed through the galvanoscope G, which is connected by wires 3' s with the plug-body 7c and its cylinder h, respectively, thus enabling the switchman to test the line. \Vhen, however, either plug is pushed into a switch sufficiently far to bring the knife-edge o of the contact-spring into contact with the insulator-ring n, the spring will be isolated both from the plug and from the switch-body,

which latter will then alone be in contact with such plug through the sleeve h.

In Fig. 6 I have shown the connections between lines L and L of two subscribers A and B by inserting the plugs S S (connected by wire 3 in which a closing-signal S K may be included, as shown) into the switches of boards III and III, respectively, as shown in said Fig. 6, the springs 11 b of both switches being isolated from their respective plug-bodies by the insulation n. The two lines L and I are therefore connected through the switches of boards I II and I II, respectively, the switchbodies and plugs of boards III and III and the connection 3 through closing-signal S K, the drops K and K, as well as the battery B, being out out of the circuit. Ifnow the switchman at one of the boards to the left of III or III desires to test the line-say, for instance,

the switchman at board Ihe inserts his testplug S into the jack-switch at said board, so

follows, for instance: line L, switch-body (I, at-

board I, plug S, its sleeve h, wire 8, galvanoscope G, wire 3, body is of plug S, spring I), switches of boards II III, plug S of the switch of last-named board connections 3 and its closing-signal S K, switch at board III, and through its plug S to switches of boards II and I to line L. If the galvanoscope remains unintluenced,the switchman is advised that the lines are in use, because thetest-battery is then cut out; but should the lines be clear the gal- Vanoscope index or needle will be deflected,

the test-battery B being then in line. The same conditions exist should a switchman at a board to the right of those III or III test the lines, as will be readily understood. The test-plug S can also be connected with the telephone of the switchman, as'shown in Fig. 7. The Wire '8 of the test-plug is connected with the fulcrum t of the lever, the contact 25 of which lever is connected with the telephone, While the contact 25 of said lever is connected with the alarm-battery W B, which latter, as well as the telephone, is grounded in a wellknown manner. The operation of these devices is as follows: When a call is made byA, the annunciator-drop of the calling-telephone drops and the switchman inserts the test-plug S into the switch of the caller, so that the knife-edge 0 of the contact-spring b will lie in the annular groove m of the plug. The switch-body is thus connected with the switchmans telephone, as shown in Fig. 7, thus placing the caller and the switchman into communication. Having ascertained the wishes of the caller, the switchman removes the test-plug and introduces a connecting-plug S into the switch, which will show that this particularline is occupied when tested at any one of the other switchboards. After this the test-plug S is gradually introduced into the switch of the called telephone B until the knife-edge 0 of the contact-spring b snaps moved and a connecting-plug S substituted therefor. If B is called directly by A, instead of being called from the central office, then the test-plug may be removed immediately after the line has been found clear and a connecting-plug S substituted therefor.

The described operation may be materially simplified by constructing the last of the sev-- eral interconnected switchesnameiy, that at the last board of the system, as shown in Figs. 8 and 9. In this construction the switchbody is provided with two springs b and f, which are insulated, as above described, from the switch-body at the point of connection, as described. The spring b is provided with a block or projection 'i of insulating material, and the spring f has the knife-edge 0, hereinbefore referred to, and ablock or plate of insulating material 1'', at its free end. In their normal position the free ends of both springs bear upon the sleeve to of the switch-body a, from which sleeve the spring f is insulated by the insulation 1'. If a connecting-plugs is inserted into the switch, so that the knifeedge 0 of spring f will lie in the annular groove m of said plug, the spring I) will be insulated from the plug as well as from the switch-body, while the spring f will have a metallic connection with the plug. If, on the other hand, the plug S is fully pushed into the switch, the spring f will alsobe isolated from the plug, the knife-edge 0 of said spring being then in contact with the insulating-ring n of the plug. The springs f of all the switches are connected with the switchmans apparatus, as shown in Fig. 10, such apparatus comprising the alarm-lever T, alarm-battery W B, telephone F, microphone M, and microphone-battery M B. The two wires 8 s of the plugs S S are directly connected together,

so that the connection of two telephone-lines is here effected by a connecting-plug S and a.

test-plug S. The switches shown in Figs. 8 and 9 are at that switchboard which has the annunciator-drops K, Fig. 10, of the corresponding telephone lines, and this switch may therefore be called the annunciatorswitch to distinguish the same from the other switches.

The operation of the apparatus, Fig. 10, is as follows: If telephone A, line L, calls, the annunciator-drop falls and the switchman inserts a plug S, Fig. 4, into the corresponding annunciator-switch III, so that the knife-edge 0 of springfwill snap into the groove m of the plug to connect A,line L, with the switch- ,mans apparatus, the annunciator-drop being thus cut out of circuit by the interruption of the contact between spring 6 and the switchbody a, a through the plug S, from which said spring is isolated by the insulation '6, thus establishing communication between A andthe switchman. If A expresses the desire to communicate with B on line L, the switchman will first test the line by inserting a test-plug S into the switch of Bfor instance, at the board IIIuntil the knife-edge of spring I) snaps into the annular groove of plug S. As the switchman is now connected with the receivinginstrument 7 through switch-spring f, he can by listening ascertainvwhether the line be clear or not. If, on the contrary, the line is tested at board II, the galvanoscope will remain uninfluenced if the line is not clear, while if the line is clear the,

circuit of battery B will be closed through K, switch-spring b at board III, switch-spring I) at board II, head of plug S, wire 8', galvanoscope G, wire 3, sleeve of plug S, and the switches of boards II I and line L. The current from battery 13 deflects the needle of the galvanoscope, thereby indicating the line to be clear. The current is in this latter case, however, divided at the galvanoscope through .9 plug S, springf of switch III to the telephone of the switchman of line L; but this has no influence upon the test and does not, therefore, come into consideration. If the galvanoscope shows the line to be clear, the switchman moves the plug S into its sec ond positionnan1ely, he pushes said plug fully into the switch, thereby interrupting the contact between spring Z) and the switch and cutting theannunciator-drop K, battery B, and line s out of circuit. After A has been advised of this the plug S is also moved into its second position, thereby cutting out the switchmans telephone, since the spring f will then be in contact with the insulation n of the plug. The current now passes from L to s, G, and s to L, the galvanoscope remaining in circuit for the reception of the closingsignal.

In Fig. 11 I have shown a simplified arrangement for testing the line, the constructioii of the test-plug S being modified accordingly and consisting of the metallic or conductive portion k and the insulated portion Fig. 12, the testing of the line being effected as follows: Supposing the line to be free and the test-plug inserted into the jackswitch of board II, the current from battery B will flow to galvanoscope G, metallic portion 70 of test-plug sleeve a of jack-switch, line 1, spring Z) of jack-switch at board I, its sleeve a, line Z, telephone-lever .9 call VV to earth. If, on the contrary, the line is in use, and supposing the telephone F to have been removed from itslcver s the subscriber communicating either with the main station or connected with another subscriber through switch III, there will be no current from battery 13"" on account of the condenser E. If the test-plug is inserted into switch I to isolate a from b, there will be no current from B, showing the line to be occupied. The described operation may, however, be further simplified, as shown in Fig. 13,con nections between four telephone-lines and as many switchboards being therein shown, the several telephones and their respective lines being indicated by L L L and L, respectively, and the switchboards by S S S S respectively.

The telephone-lines have at each switchboard a switch such as shown in Figs. 2 and 3, the four switches for line L being indicated by I' ,II, III, and IV, the switches for lines L L and L being indicated by the same Roman numerals with their respective letters B, O, and D annexed thereto. On the other hand, that switchboard which is provided with the annunciator-drop for any particular line is also provided with an additional switch, such switches being indicated at I II III IV, the annunciator-drops being indicated by K, K, K", and K re spectively, and correspond with the telephone lines L L &c. All the annunciator-drops are grounded, theybeing connected. to a con1- 111011 rail IV and the latter to a resistance W, which in turn is connected with battery B.

Each switchboard is further provided with a switch-lever U and a switch composed of two springs q and 1), respectively, connected with lines s and s. The line .9 is connected to the body of plug S, while the line 3 is connected with the insulated cylinder 72. of plug .9, said springs q and 1) bearing upon contacts 1' 7', respectively, when in their normal position, said contacts being connected with the throughrails II and I. In the circuit of the contacts it and q; is arranged the closing-signal S K. The body 7.; of the plugs S is connected by wire 3' with the through rail III and the galvanoscope G as a line-tester is in the circuit of the through-rails II and III, while the operators apparatus consisting of the telephone F, microphone M, i11duction-coil.I,and battery M B is connected with rail I. The telephone F is also connected with the lever T, and through the latter with rail III on the one hand and the condenser O on the other, said condenser being grounded and prevents the branching of the test-current to ground and to the telephone apparatus and renders the latter more efficient, especially in that the disturbing noises due to ground-currents are very materially lessened. The adjustable resistance W here shown serves the purposes previously described.

The operation of the described arrangement of devices is illustrated in its various steps at the different switchboards, it being taken for granted that the plugs S and S of one board only are brought into operation at one and the same time.

Board I shows the connections of the switchmans telephone when called by telephone L the line being clear and the annunciatordrop K having dropped. The switchman introduces the plug S into switch I, and the current from line L passes successively through the switches II III, IV, I, and I, plug S, line 3 to q 1' railI, to telephone F, to ground. Board S II shows the manner of testing the line to be connected. It is here assumed that line L called and is connected with the 0perators telephone apparatus, as described in reference to board S I, through the medium of a plug S. The operator has to connect the calling-telephone with telephone L. For the purpose of testing the line the plug S is iii-n serted into switch II, so that the spring thereof will be in electrical connection with the body 70 of the plug, whereby the galvanoscope G is circuited through the plug-line s and rail III 011 the one hand and on the other through plug-line .9, spring 19, and rail II. If

the line L is clear, the needle of the galvanoscope will be deflected for the reasons already stated. Board S III shows 110w after testing the line the two subscribers are connected and how this connection is controlled by the operator. It is here assumed thatsubscriber L has called the central office and desires to communicate with A and that the line L has been tested by the operator. If the line is clear, the plug S is fully inserted into switch III whereby the connection be tween III with IV, (board S IV,) IV, rail IV, and battery B is interrupted, while the telephone apparatus of the switchman at the board S III remains in circuit. The currentarriving from line L will pass through switches IV I II III III plug S, board S III,

v plug-line s springp, railI, telephone F, lever T, rail III, galvanoscope G, rail II, spring (1, plug-line s, to the cylinder h of plug S, thence to switches III II I to L'-' By pressing upon leverT as to assume the position shown in dotted lines at the board S III the switchman can set the alarm at the called telephone L in operation. As soon as the connection is made the switch U is turned to bring the springs 19 q in contact with the contacts u and o, respectively, whereby the telephone apparatus of the operator and the galvanoscope G are out, out while the terminal signal-drop S K is included in the circuit of the two subscribers. This part of the operation is shown at the board S IV. It is here assumed that L A and L are in communication, as hereinbefore described. The connection is from L through L, I II, III*, IV, IV plug S, plug-line 8 spring q, contact to, annunciator-drop S, K contact 1), spring 19, plug-line s, plug S, switch IV III II to L 13. If the terminal signal is given, the lever S K falls, the conversation is ended, and both plugs S and S are withdrawn from their switches, andinsaid Fig. 13 the annular groove m of the switch-plugs is not shown, owing to the small scale to which these plugs are drawn.

It from any cause it becomes desirable not to use the battery B at the central oflice, the same arrangement of switchboards and connections, as described, may be employed with the following modifications:

As shown; in Fig. 11, a small condenser O is included in each telephone-line between the telephone and the earth at each subscribers station, the telephone being normally suspended from a hook on a lever f pivoted at s The weight of the telephone holds the lever in contactwith rfiwhose line is grounded through a resistance WV which in this case is the call-bell of the subscriber. When the telephone is removed from the lever f the latter of its own weight moves in contact with a thereby interrupting the ground-circuit and establishing the telephone-circuit. This connection can be used with ordinary telephones, as well as with microphones, and has the advantage of materially lessening the noises present in long single lines, and notwithstanding the weakening of transmitted speech the articulation is better or made plainer and more comprehensible than with the ground connection. The test-plug here employed is shown in Fig. 12, and consists of two massive or solid portions 10 of which the former is metal and the latterof insulating material. In the line of this plug is included a test galvanoscope and a battery with ground connection, so that the battery B can be dispensed with. In testing a line with this plug it is inserted into a switch, Fig. 2, so as to isolate the spring 19 thereof through the portion 70 of the plug to interrupt the circuit to the righti. a, to ground or end of linewhile the metallic portion 10 of the plug is in contact with the switch-body a. If the line to be tested is in use, the galvanoscope will remain unaffected, while its needle will be deflected if the line isclear, substantially as hereinbefore set forth. In this arrangement a test toward the left only can be made for the reason that the portion 70 of the testplugis insulated. This is,however, of no consequence, since the left portion of the line is to be tested only, and in view of this the difference of construction between the test-plug last described and that shown in Fig. lis necessary to avoid a closed circuit to the right, which would lead to errors.

For the connections a plug similar to that employed for testing the line is used and a plug similar to that shown in Fig. 4.

The switches are, as shown in Fig. 14, so arranged as that the lowermost row of switches a will lie in a horizontal plane, while the succeeding superposed rows will'have a gradually-increasing inclination from a horizontal toward a vertical, so that the upper row of switches will have an inclination of about thirty degrees. This arrangement very materially facilitates the insertion of the plugs, as the plane of the switches more nearly corresponds with that of the arm of the operator in reaching upward to insert or withdrawa plug. The latter are connected with lines 3 that are held under tension by means of weights suspended from rollers .9

Having described my invention, what I claim, and desire to secure by Letters Patent, 1s

1. In multiple switchboards, a jack-switch comprising a switch-body one end of which is tubular, and a contact-spring having a V- shaped portion 0 and being secured to but insulated from said switch-body in such manner that the free end of the spring will normally contact with the tubular portion of a switch-body, and a telephone-line electrically connecting the switch-body of one jack-switch with the contact spring of the next jackswitch throughout the series of the same telephone-line, in combination with a test-battery interposed in the ground connections of the terminal switch of a series of such, for the purpose set forth.

2. In a system of multipleswitchboards, the combination, with the switches of a telephone,constructedandconnectedasdescribed, of a three-part switch composed of a body a, a contact-spring I), provided with a projection i, of insulating material, the free end of which spring lies in contact with the switch-body when the parts are in a normal state, and a contact-springf, that is permanently isolated from the switch-body, substantially as and for the purposes specified.

3. In multiple switchboards, the combination, with a series of jack-switches com prising a switch-body one end of which is tubular and a contact-spring secured thereto and insulated therefrom at the point of attachment, the free end of said spring normally coutacting with the tubular portion of the switchbocly, electrical connections connecting the switch-body of one jack-switch with the contact-spring of the next throughout the series of switches in the same telephone-1i no, and a telephone-line electrically connected with the tubular portion of one of the contact-switches of the series, of a line-tester comprising a galvanoscope, a test-plug composed of two elements insulated from each other and connected with the terminals of the coil of the galvauoscope, a local telephone-circuit, and a switch-lever interposed therein and connected with the galvanoscope-circuit, for the purpose set forth.

4. In multiple switchboards, the combination, with the switches of the telephone-lines, comprising a switch-body one end of which is tubular and a contact-spring secured thereto and insulated therefrom at the point of attachment, the free end of said spring normally contacting with the tubular portion of the switch-body, a telephone-line electrically connected with the switch-body of the initial jack-switch of a series, and electrical connections connecting the switch-body of one switch with the contact-spring of the next switch throughout the series, of a test-plug composed of two elements insulated from each other, a galvanosoope having the terminals of its coil respectively connected with said elements, a plug S, also connected with one of the terminals of the galvanoscope-coil, and a telephone in the ground branch of one of the lines, for the purpose set forth.

5. In multiple switchboards, the combination, with the jack-switches of the telephoneliues, comprising a switch-body one end of which is tubular and a contact-spring secured thereto and insulated therefrom at the point of attachment, the free end of said spring normally contacting with the tubular portion of the switch-body, a terminal switch from one end of said lines having a like tubular portion, and two contact-springs b and f, secured thereto and insulated therefrom at the point of attachment, said springs being provided with insulators iand 1', respectively arranged as set forth, and a telephone in the ground connections of one of the springs of the terminal switch of one of the series, of a linetester comprising a galvanoscope, two plugs S and the two-part plug S, said plug S and one of the elements of the plug S being connected to one of the terminals of the galvanoscope and the other element of plug S with the other terminal of said coil, for the purpose set forth.

6. In multiple switchboards, the combination, with the described auxiliary jack-switch, ot' the plugs S and S, the rails I, II, and III, the contact-springs p and (1, electric connections between the spring 9 and one element of plug S and between the other element of said plug and the rail III, a like connection bet-ween the spring 1 and plug S, a galvanoscope having the terminals of its coils con nected with rails II and III, a telephone-circuit connected with rails I and IIIJthe contacts r and 7- respectively connected with rails I and II, and the switch-lever U, for the purpose set forth.

7. In multiple switchboards, the combination, with the described auxiliary j tick-switch, the rail IV, connected with the contact-spring of said switch, and an annnnciator-drop in said connection, of the plugs S and S, the rails I, II, and III, the contact-springs p and q, electric connections between the spring 29 and one element of plug S and between the other element of said plug and the rail III, a like connection between the spring q and plug S, a galvanoscope having the terminals of its coils connected with rails II and III, a telephone-circuit connected with rails I and III, the contacts 7' and 0- respectively connected with rails I and II, and the switch-lever U, for the purpose set forth.

8. Inmultiple switcl1boards,'tl1e combination, with the described auxiliary jack-switch, of the plugs S and S, the rails I, II, and III, the contact-springs p and q, electric connections between the spring 13 and one element of plug S and between the other element of said plug and the rail III, a like connection between spring 19 and plug S, a galvanoscope having the terminals of its coils connected with rails II and III, a telephone-circuit connected with rails I and III, the contacts and 0' respectively connected with rails I and II, an aununciator-circuit having contacts u and o in proximity to the springs 12 and q, and the switch-lever U, for the purpose set forth.

9. In multiple switchboards, the combination, with the described auxiliary jack-switch, the rail IV, connected with the contact-spring of said switch, and an annunciator-drop in said connection, of the plugs S and S, the rails I, II, and III, the contact-springs p and q, electric connections between the spring 1) and one element of plug S and between the other element of said plug and the rail III, alike con ncction between the spring q and plug S, a galvanoscope having the terminals of its coils respectively connected with rails II and III, a telephone-circuit connected with rails I and III, the contacts 0 and 0*, respectively connected with rails I and II, an annunciator-circuit having contacts u and 'u in proximity to the springs 19 and'q, and the switch-lever U, for the purpose set forth.

10. In multiple switchboards, the combina tion, with the described auxiliary jack-switch, the rails I, II, and III, the line-tester comprising the plugs S and S, the contact-springsp (1, respectively connected with one of the elements of plug S and with plug S, a connection between the other element of plug S and rail III, a galvanoscope having its terminals connected with rails II and III, the contacts 4" T respectively connected with rails II and I, and the switch-lever U, adapted to operate the springs 19 q, of a telephone-circuit connected with rails I and III and a switch-lever interposed therein between the telephone and said rail III, for the purpose set forth.

11. In multiple switchboards, the combination, with the described auxiliary jack-switch, the rails I, II, and III, the line-tester comprising the plugs S and S, the contact-springs p q, respectively connected with one of the elements of plug S and with plug S, a connection between the other element of plug S and rail III, a galvanoscope having its termi nals connected with rails II and III, the contacts 0- 7 respectively connected with rails II and I, and the switch-lever U, adapted to operate the springs 19 q, of a telephone-circuit connected with rails I and III, a switchlever interposed therein between the telephone and said rail III, and a condenser in- WILHELM OESTERREICH.

Witnesses GEORGE LOUBIOR, ADOLF DEMELIUS. 

